To provide a silicone gel composition excellent in vibration-isolating characteristics and having good adhesivity to a substrate, handleability and self-retainability of fluidity.

This silicone gel composition comprises (A) 100 pts.wt. of polyorganosiloxane expressed by general formula (1) (wherein, R1s are the same or different and each represents a methyl group or a phenyl group; n and m are integers satisfying 0≤n/(n+m)≤0.3) and having 0.1-200 Pa s viscosity at 25°C, (B) 5-100 pts.wt. of polyisobutylene having at least two alkenyl groups in one molecule, (C) a polyorganohydrogensiloxane having at least two hydrogen atoms each bonded to a silicon atom [in such an amount that the ratio of the total of the mole number of vinyl groups in the component (A) and the mole number of alkenyl groups in the component (B) to the mole number of hydrogen atoms each bonded to a silicon atom is 1:0.2-5] and (D) a platinum-based catalyst [in such an amount that the weight of the platinum atom in this component is 0.1-100 ppm to the component (A)]. The composition gives a cured product having JIS A hardness (JIS K 6253 Type A) of 0 and penetration (JIS K 2220) of 30-150.